Flexible part carrier strips for holding and transporting pre-formed parts are commonly employed in the automated manufacture of electronic and other components. Many electronic components are manufactured using robotic loaders and other automated assembly devices in order to maximize the efficiency of the production line. Automated assembly machines typically have a loading arm which retrieves the part from a pre-designated location and inserts the part in place on a component being assembled on the production line, such as an electronic circuit board. The part is then soldered, welded, or otherwise connected to the circuit board by another automated step further down the assembly line. Such automated assembly devices are commonly used in the construction of electronic circuit boards and other electronic devices.
In order to maintain the efficiency of the production line, the component parts must be presented to the automated loader at a consistent pre-determined location, and at a consistent pre-determined orientation. Any deviations from the desired orientation or location will result in defective assembly of the final product. In order to ensure the proper presentation of the part to the loading device, most automated assembly lines utilize carrier strips, carrier tapes, or carrier trays to deliver a properly oriented part to the pickup point.
On a typical carrier tape or strip, the oriented parts are secured at precise intervals along a flexible continuous strip of plastic. The steps of forming the part and securing the part to the carrier strip is usually performed away from the automated assembly line. The strip holding the parts is then rolled, transported, and fed into a loading machine on the assembly line using a commercially available feeding device. On many component parts, it is necessary to have a plurality of legs or projections extending from the part, which legs or projections are aligned with and received by a plurality of corresponding recesses in the part carrier strip. For example, one type of carrier strip known under the tradename "GPAX" is described in U.S. Pat. Nos. 4,583,641 and 4,757,895. The GPAX structures disclose a carrier tape having a plurality of part receiving recesses and intervening slots punched along the length of the strip. The recesses are adapted to engage the legs, stubs, or leads on the part, and the part is secured to the strip using a plastic bonding tape which overlays the parts.
Another carrier strip structure, known as "debossed tape and reel" consists of a plastic carrier tape with a plurality of recesses or pockets along the length thereof in which the parts are placed. A sealing tape is bonded over the length of the carrier tape in order to retain the parts within their respective pockets. The carrier tape is fed into the robotic loader, which peels away the sealing tape, removes the part, and then discharges both the carrier tape and the sealing tape to waste. The debossed tape and reel structure is best suited for flat parts, and the two-part disposable nature of the tape and reel method is very expensive.
One such component part frequently installed on the finished electrical device is a Radio Frequency shield (RF shield). An RF shield covers a selected electronic component in order to protect that selected component from electrical interference. RF shields, like other discrete elements on the finished component, are likewise loaded and assembled using automated equipment, and hence the RF shield must be adapted for use with a part carrier strip.
Unfortunately, RF shields typically lack electrical leads or other structures which could be used to orient the RF shield and secure the RF shield to the carrier strip. Thus, many RF shields are equipped with a series of sidewall perforations, which perforations are engaged by a plurality of projections or lugs surrounding the part receiving area on the carrier strip. Although the sidewall perforations enhance the ability of the RF shield to be carried on the carrier strip, the sidewall perforations degrade the protective effects of the RF shield, often to an unacceptable degree. RF shields having perforated sidewalls are often unacceptable for use on high frequency applications.
Accordingly, there exists a need for an improved and flexible part carrier strip which is well-suited for securing and transporting RF shields, and for an RF shield for use therewith having no sidewall perforations.